Research and Reviews: Journal of Pharmaceutical Analysis Liquid Chromatographic Estimation of Epalrestat and Methylcobalamin in Pharmaceutical Formulation. Krima R Patel *, Dimal A Shah, Falgun A Mehta, Usmangani K.Chhalotiya, Kashyap K Bhatt. Indukaka Ipcowala College of Pharmacy, Beyond GIDC, P.B. No. 53, Vitthal Udyognagar- 388 121, Gujarat, India. Research Article Received: 13/01/2014 Revised: 28/02/2014 Accepted: 05/03/2014 *For Correspondence Indukaka Ipcowala College of Pharmacy, Beyond GIDC, P.B. No. 53, Vitthal Udyognagar- 388 121, Gujarat, India. Mobile. No.: +919428444358 Keywords: Epalrestat (), Methylcobalamin (), Liquid Chromatography, Validation ABSTRACT A sensitive, selective and precise high performance liquid chromatographic method has been developed and validated for the simultaneous determination of Epalrestat and Methylcobalamin both as a bulk drug and in formulation. The method employed Luna C18 column (250 x 4.6 mm id, 5 µm particle size) as the stationary phase while acetonitrile: 0.02 M KH2PO4 buffer (90:10 v/v, ph 6.5) was used as mobile phase. The Rt of Epalrestat and Methylcobalamin were observed to be 5.2 and 2.1 minutes, respectively. Analysis was carried out in absorbance mode at 254 nm. The linear regression analysis data for the calibration plots showed a good linear relationship for Epalrestat and Methylcobalamin over a concentration range of 1-40 µg/ml and 0.2-10 µg/ml respectively with correlation co-efficient of 0.9995 for epalrestat and 0.9991 for methylcobalamin. The LOQ was found to be 0.2 µg/ml for epalrestat and 0.8 µg/ml for methylcobalamin. The method was validated as per ICH guideline and it was found to be accurate, precise and robust. Marketed formulation was analyzed successfully INTRODUCTION is chemically 2-[(5Z)-5-[(E)-3-phenil-2-methylprop-2-enylidene]-4-oxo-2-thioxo-3-thiazolidinyl] [1, 2]. Epalrestat work by inhibiting Aldose Reductase Enzyme [3]. is chemically 3-[({2-[(diaminomethylidene) amino]- 1, 3-thiazol-4-yl} methyl) sulfanyl]-n'-sulfamoylpropanimidamide [4, 5]. is active form of vit B12. It is used for the treatment of peripheral neuropathy, diabetic neuropathy [6, 7]. Literature survey revealed there is no published chromatographic method for this combination of drug. The present paper describes a simple, accurate and precise method for reverse phase liquid chromatographic estimation of and in combined tablet dosage form. The proposed method is optimized and validated as per the International Conference on Harmonization (ICH) guidelines [7]. In the present work, a successful attempt has been made to estimate both these drugs simultaneously by RP-HPLC method. Instruments MATERIALS AND METHODS Instrument Perkin Elmer USA, Series 200, Phenomenex Luna C18 column (250 x 4.6 mm id, 5μm particle size) was used for analytical method development. The chromatographic data were processed by Totalchrom navigator HPLC version 6.3.1 Software. Materials Epineurone Tablet (50mg and 0.5mg ) manufactured by Aristo Pharmaceutical Ltd. All chemicals and reagents used were of AR grade. Reagents All the chemicals used were of AR grade. RRJPA Volume 3 Issue 2 April - June, 2014 35
Selection of Analytical wavelength The sensitivity of HPLC method that uses UV detection depends upon proper selection of detection wavelength. An ideal wavelength is the one that gives good response for the drugs that are to be detected. Overlay UV spectra of both the drugs showed that and absorbed appreciably at 254 nm, so detection was carried out at 254 nm (figure 1). Preparation of Mobile Phase Figure 1: Overlain spectra of and (10μg/ml each) Buffer 0.02 M KH2PO4 was prepared by weighing 2.72 g of KH2PO4 and dissolving in 1000 ml of water. Mobile phase was prepared by mixing 100 ml of 0.02M KH2PO4 Buffer and 900 ml of acetonitrile. The ph was adjusted to 6 using o-phosphoric acid (1%) or triethyl amine (1%) of the mobile phase was 6. Solution was filtered through Whatman filter paper No. 41 and sonicated for 10 min and this solution was used as a mobile phase. Preparation of Standard Stock Solutions (10 mg) and (10 mg) were accurately weighed and transferred to two separate 10 ml volumetric flask and dissolved in few ml of acetonitrile. Volumes were made up to the mark with acetonitrile to yield a solution containing 1000 μg/ml of and 1000 μg/ml of, respectively. Appropriate aliquot from above solutions were taken and diluted with mobile phase to obtain final concentration of 100 μg/ml and 100 μg/ml of and respectively. Chromatographic conditions Phenomenex Luna C18 column (250 x 4.6 mm id, 5μm particle size) chromatographic column equilibrated with mobile phase 0.02M KH2PO4 buffer: acetonitrile (10:90, v/v) was used. Mobile phase flow rate was maintained at 1 ml min-1and effluents were monitored at 254 nm. The sample was injected using a 20 μl fixed loop, and the total run time was 7 min. Calibration Curve for and Appropriate aliquot of stock solution of and was taken in same 10 ml volumetric flasks. The volume was made up to the mark with mobile phase to obtain final concentration of 1, 5, 10, 20, 40 μg/ml of and 0.2, 0.5, 1, 5, and 10 μg/ml of, respectively. Validation Parameter Linearity The calibration curve for was found to be linear in the range of 1-40 μg/ml with a correlation coefficient of 0.9995. The calibration curve for was found to be linear in the range of 0.2-10μg/ml with a correlation coefficient of 0.9991. The regression analysis of calibration curves is reported (Table 1, 2) (figure 3, 4). RRJPA Volume 3 Issue 2 April - June, 2014 36
Area Area Figure 2: Acetonitrile: 0.02 M KH2PO4 (90:10% v/v) (ph 6.5) 400000 300000 200000 100000 0 0 10 20 30 40 50 conc Figure 3: Calibration curve for 200000 150000 100000 50000 0 0 2 4 6 8 10 12 conc Figure 4: Calibration curve for Precision Intraday precision The intraday studies were carried out by measuring response for 3 concentrations for 3 times a day. The % RSD was found to be 0.74-1.27 % for and 0.77-1.52 % for (Table 3, 4). These %RSD value was found to be less than ± 2.0 indicated that the method is precise. Interday precision The interday studies were carried out by measuring response for 3 concentrations for 3 times at 3 different days. The was found to be 0.76-2.01% for and 0.78-2.14 % for (Table 3, 4). These %RSD value was found to be less than ± 2.0 indicated that the method is precise. RRJPA Volume 3 Issue 2 April - June, 2014 37
Repeatability study The repeatability studies were carried out by measuring response for a single concentration for 6 times a day. The was found to be 0.42% for and 0.46% for (Table 5). These %RSD value was found to be less than ± 2.0 indicated that the method is precise. Accuracy The accuracy of the method was determined by calculating recoveries of and by method of standard addition. The recoveries found to be 100.56% -101.71 % and 109.18%-111.91% for and respectively. The high values indicate that the method is accurate (Table 6). Limit of detection and limit of quantification LOD is the lowest amount of the analyte that can be detected. From the visual observation of chromatogram, the LOD for was found to be 0.08 µg/ml and for was found to be 0.2 µg/ml. LOQ is the lowest amount of the analyte that can be detected and quantified. LOQ of the was found to be 0.2 µg/ml and LOQ of the was found to be 0.8 µg/ml. Robustness Robustness of the method was studied by changing the mobile phase composition, ph of the mobile phase and flowrate (Table 7). Solution stability Stability of standard and sample solution of and were evaluated at room temperature for 24 hr. Both the drugs were found to be stable with a recovery of more than 98% (Table 8). System suitability parameters System suitability test was carried out and the results are summarized in Table 9. Analysis of Marketed Formulation Twenty tablets were weighed and finely powdered. Tablet powder equivalent to 10 mg (and 0.1 mg ) was weighed and transferred in to a 25 ml volumetric flask containing few ml of mobile phase. The flask was sonicated for 5 minutes. The solution was filtered through Whatman filter paper No. 41 in another 25 ml volumetric flask and volume was made up to the mark using mobile phase(stock A). Estimation of was carried out from stock A at 254 nm. From the stock A appropriate aliquot was pipette out in 10 ml volumetric flask and make up the volume with mobile phase to obtain the 40 µg/ ml of (stock B). Estimation of was carried out from stock B at 254 nm. The quantitation was carried out by keeping peak area in regression equation and amount of and were determined (Table 11). Table 1: Regression analysis of calibration for by HPLC method Concentrations Area Mean ± S.D. (n=5) (μg/ml) 1 4356.854 46.52 1.06 5 35236.63 318.55 0.90 10 85397.09 401.32 0.46 20 179748.8 297.82 0.16 40 361852.5 564.06 0.15 Slope 9241.2 Intercept 7148.4 R 2 0.9995 RRJPA Volume 3 Issue 2 April - June, 2014 38
Table 2: Regression analysis of calibration for by HPLC method Concentrations (μg/ml) Area Mean ± S.D. (n=5) 0.2 7914.86±71.74 0.90 0.5 15853.46±107.09 0.67 1 24392.3±88.39 0.36 5 84431.69±184.98 0.21 10 159504.6±252.63 0.15 Slope 15253 Intercept 7475.2 R 2 0.9991 Table 3: precision data for estimation of (n=3) Conc μg/ml Intraday (n=3) %RSD Interday (n=3) %RSD (area (area) 1 4767.20 1.08 4788.12 2.01 10 87896.26 1.27 86346.00 1.32 40 363668.10 0.74 364021.10 0.76 Table 4: precision data for estimation of (n=3) Conc. μg/ml Intraday (n=3) (absorbance) Interday (n=3) (absorbance) 0.2 1 10 7399.91 1.52 7369.95 2.14 24194.20 0.77 24485.17 0.83 154970.00 0.77 154172.25 0.78 Table 5: Repeatability data for AND Concentration 6 µg/ml Rt (Min) 50 µg/ml Rt (Min) Area 85496.51 5.21 24356.25 2.13 85503.38 5.21 24378.94 2.14 85400.92 5.22 24329.36 2.11 85193.56 5.21 24468.35 2.13 84901.98 5.23 24375.23 2.13 85985.63 5.21 24463.65 2.14 Mean. 85413.67 5.21 24395.29 2.13 Std. Dev. 361.2412 0.0076 57.5351 0.0195 0.42 0.14 0.23 0.46 RRJPA Volume 3 Issue 2 April - June, 2014 39
Table 6: Accuracy data of and (n=3) Amount of drug added initially from formulation Amount of standard drug added (μg/ml) % recovery ± SD (n = 3) %RSD 10 1 0 0 100.56± 111.65± 1.00 1.70 0.92 1.70 10 1 5 0.5 101.40±0.51 109.18± 0.52 1.56 1.52 10 1 10 1 103.20± 110.72±0.62 0.50 0.66 0.49 10 1 15 1.5 101.71± 0.41 111.91±0.51 0.49 0.52 % recovery ± SD (n = 3) Amount of standard drug added Table 7: Robustness studies of HPLC method Parameter ph Mobile phase Ratio Acetonitrile: 0.02 M KH2PO4 Method RT of peak area condition 6 5.28 2.01 0.47 0.57 7 5.11 1.89 0.45 0.52 85: 15 19.64 2.35 0.42 0.62 95: 05 3.47 2.02 0.39 0.71 Table 8: Solution stability study Time (Hrs.) 10 ( g/ml) Area (n=3) 1 ( g/ml) % RECOVERY 0 85260.22 22728.12 100 100 3 84965.42 22557.54 99.65 99.25 6 84650.86 22675.72 99.27 98.77 24 84366.75 22330.26 98.95 98.25 Table 9: System suitability study Parameters Asymmetric factor 1.15 1.1 Resolution 3.08 Theoretical plates 3630.71 4672.46 RRJPA Volume 3 Issue 2 April - June, 2014 40
Table 10: Summary of Validation Parameters of HPLC Parameters Range 1-40 g/ml 0.2 10 g/ml Retention time (min) 5.21 2.13 for Retention time 0.14 0.46 Asymmetric factor 1.15 1.1 Resolution 3.08 Theoretical Plates 3630.71 4672.46 Detection limit ( g/ml) 0.08 0.2 Quantitation limit ( g/ml) 0.2 0.8 Accuracy (%) 100.56% -101.71 % 109.18%-111.91% Precision (%RSD) Intra-day (n=3) 0.74-1.27 % 0.77-1.52 % Inter-day (n=3) 0.76-2.01% 0.78-2.14% Repeatability (%RSD) 0.42% 0.46% Robustness Robust Robust Specificity Specific Specific Table 11: Analysis of marketed formulation Labeled Formulation Amount (mg) Amount found (mg) % Of drug found SD (n=3) EPINEURONE 40 4 39.8 4.5 99.50 0.8371 113.54 0.0111 CONCLUSION The RP-HPLC method for the simultaneous estimation of and has been developed. The method was validated as per ICH Q2 (R1) guideline for accuracy, precision, linearity, specificity and robustness. The developed method was successfully applied to marketed formulation. REFERENCES 1. Japanese Pharmacopoeia; 16th Edn; the Ministry of Health, Labour and Welfare: the controller and publication, Japan, p. 2404-2406; 2011. 2. The Merck Index-An Encyclopedia of Chemicals, Drugs and Biological; 14th Edn; Merck CO. Inc., Whitehouse, p. 3608; 2001. 3. Martindale - The Extra Pharmacopoeia; 31st Edn; The Royal Pharmaceutical Society, London, p. 346; 1996. 4. Japanese Pharmacopoeia; 16th Edition, The Ministry of Health, Labour and Welfare: The Controller and Publication, Japan, p. 1066, 1068; 2011. 5. Martindale - The Extra Pharmacopoeia; 31st Edn; The Royal Pharmaceutical Society, London, p. 2116; 1996. 6. Hardman JG, Limbird LE. Goodman & Gilman s Manual of Pharmacology and Therapeutics; 10th Edn; McGraw- Hill, New Delhi, p.1505-1510; 2011. 7. Aguilar F, Charrondiere U, Dusemund B, Galtier P, Gilbert J, Gott D. M, Grilli S., Scientific Opinion Of the Panel on Food Additives and Nutrient Sources Added to Food. The EFSA J.2008:1-21. 8. ICH guidelines, Validation of Analytical Procedures, Text and Methodology Q2 (R1); I.C.H. Tripartite Guidelines, p. 5-17; 2005. RRJPA Volume 3 Issue 2 April - June, 2014 41
9. Shirkhedkar AA, Nankar CS, Surana SJ, et al. Quantitative determination of epalrestat by RP-HPLC method. Eurasian J Anal Chem. 2012; 7(1):49-55. 10. Pathi JP, Appala RA, et al. The estimation of epalrestat in tablet dosage form by RP-HPLC. Asian J Pharm Anal. 2012; 2(2):49-51. 11. Saravanan J, Shajan A, Joshi NH, Varatharajan R,Valliappan K, et al. A simple and validated rp-hplc method for the estimation of methylcobalamin in bulk and capsule dosage form. Int J Chem Pharm Sci. 2010; 1(2):13-16. 12. http://www.inventi.in/article/ppaqa/335/12.aspx. 13. Tala P, Paghadar B, Dhudashia K, Bhaliya T, Nariya A, et al. Analytical method development and validation for simultaneous estimation of duloxetine hydrochloride and methylcobalamin in their pharmaceutical dosage form by absorption correction method. Int J Res Pharm Nano Sci. 2013; 2(2):213-220. 14. Shete AS, Lade PD, Inamdar SJ, Kumbhar SS, Mhadeshwar AP, et al. Simultaneous estimation of duloxetine hydrochloride and methylcobalamin by using spectroscopic method. Int J Pharm. 2013; 3(4):734-740. 15. Galande VR, Baheti KG, Dehghan MH, et al. UV-Visible spectrophotometric method for estimation of gabapentin and methylcobalamin in bulk and tablet. Int J Chemtech Res. 2010: 2(1):695-699. 16. Muthukumar S, Reddy S, Selvakumar D, Banji D, et al. Development and validation of RP-HPLC method for the quantification of piarcetam and mecobalamin. Int J Bio Pharm Res. 2013; 4(10):681-684. 17. Vaidya KR, Shantaram IN, Gaikwad J, et al. Method development and validation for the simultaneous estimation of b-group vitamins and atorvastatin in pharmaceutical solid dosage form by RP-HPLC. Int J Pharm Chem Bio Sci. 2013: 3(2):330-335. 18. Narmada P, Vijayalakshmi G, Nali G, Gowtham Y, Subasini B, Jogi K V, et al. RP-HPLC method development and validation for the determination of methylcobalamin and pregabalin combined capsule dosage form. Int. J. of Res. Pharm. Sci. 2013; 4(1):25-29. 19. Kannapan N, Nayak SP, Venkatachalam T, Prabhakaran V, et al. Analytical RP-HPLC method for development and validation of pregabalin and methylcobalamin in combined capsule formulation. J App Chem Res. 2010; 13:85-89. 20. Bhatt KK, Patella EM, Mori A, et al. Simultaneous estimation of pregabalin and methylcobalamin in pharmaceutical formulation by RP-HPLC method. Anal Bioanal Tech. 2013; 4(1): 2-4. 21. Pai NR, Sawant SS, et al. A simple and validated RP-HPLC method for the estimation of methylcobalamin and alphalipoic acid in soft gelatin capsule dosage form. Der Pharmacia Sinica. 2013; 4(5):46-53. RRJPA Volume 3 Issue 2 April - June, 2014 42